The objectives of the Nutrition Core are to consolidate resources and provide support needed for adequate nutrition, body composition and physical activity assessment in the associated projects, and to conduct research required for continuing refinement of related methodology appropriate to cancer prevention control projects. Specific aims include 1) Supervision of design, collection, and interpretation of biochemical and anthropometric indicators of nutritional status; 2) Supervision of the design and collection of all dietary and activity data; 3) Maintenance and ongoing development of appropriate food composition data bases; 4) Reduction of dietary data (coding and conversion to nutrients, food groups, or compounds of interest); 5) Provision of data to project investigators, working in close collaboration with the Biometry Core; 6) Consultation with project investigators regarding interpretation of the results; 7) Maintenance of quality control procedures for dietary, physical activity, and body composition assessment data collection, coding, and analysis; and 8) Methodologic investigation in support of the projects. The three colon cancer prevention projects (Fiber, Piroxicam, and DFMO) included in this application require ongoing nutritional status and dietary assessment components for eligibility, and to evaluate confounding and interacting nutrients. Dietary, body composition and activity data will be collected to monitor time trends, and to assess their relation to polyp recurrence. The common focus on colon polyps and the design of the three projects permit consolidation of efforts regarding dietary evaluation and activity, and will permit cross-project analyses which will extend the utility of each project's results. The Arizona Food Frequency Questionnaires (AFFQ) will be used as the basic food intake measure in the three projects. Seven random day dietary intake record data will be collected on a subsample in all 3 trials for continuing external validation of the AFFQ, and in the Fiber and Piroxicam trials for an assessment of dietary factors related to polyp recurrence. In addition, the core will also provide quality assurance analysis of the composition of all fiber supplements.